1. Field of the Invention
The present invention relates to a vehicle data recording device.
2. Description of the Related Art
Recently, a vehicle data recording device or a drive recorder employing a recording unit called a fight recorder which is installed in air planes has been researched. The vehicle data recording device records data associated with a vehicle's driving status detected by a sensor installed in a vehicle, so as to objectively carry out a post-analysis for analyzing the cause of an emergency status by the use of recorded data. For example, the emergency status may occur when impact force greater than a specific value is externally applied to the vehicle. In the vehicle data recording device, it is not practical to record data having a size which amounts to entire driving time periods due to its enormous recording capacity. For this reason, data is overwritten in a recording device in which data detected by a sensor for a predetermined time period is continuously rewritable. Further, data stored for a predetermined time period before the vehicle becomes the emergency statue is stored so as to be utilized in the post-analysis (for reference, see Japanese Unexamined Patent Publication No. 07-244064).
However, the vehicle data recording device has a drawback in that data detected by the sensor is no longer recorded after the data is recorded due to the occurrence of emergency condition. Therefore, for example, if the vehicle is under the influence of a greater impact force immediately after data is recorded in a state that impact force no less than a predetermined value is externally applied to the vehicle, the data is not recorded. As a result, there has been a problem in that a post-analysis such as a cause-analysis cannot be carried out when a further critical emergency condition occurs after the vehicle has already been under the emergency condition.